Your backend would be expected to return an error response that described
the problem, so that error messages can be generated on the app.

API responses will be translated into instances of DS.Errors differently,
depending on the specific combination of adapter and serializer used. You
may want to check the documentation or the source code of the libraries
that you are using, to know how they expect errors to be communicated.

Errors can be displayed to the user by accessing their property name
to get an array of all the error objects for that property. Each
error object is a JavaScript object with two keys: